Wang Xiaozhan, Mao Wenzhe, Fang Chun, Tian Song, Zhu Xueyong, Yang Ling, Huang Zan, Li Hongliang
Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China; Basic Medical School, Wuhan University, Wuhan, China; Institute of Model Animals of Wuhan University, Wuhan, China; Medical Research Institute, School of Medicine, Wuhan University, Wuhan, China.
College of Life Sciences, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China.
J Hepatol. 2017 Sep 6. doi: 10.1016/j.jhep.2017.08.032.
BACKGROUND & AIMS: Hepatic ischaemia-reperfusion (I/R) injury is characterised by severe inflammation and extensive cell death. Multiple signalling pathways, including NF-κB and mitogen-activated protein kinase (MAPK)/c-Jun NH2-terminal kinase (JNK), have important roles in this process. Identifying the unknown critical regulators of these signalling pathways could provide potential targets for therapeutic application. Dual-specificity phosphatase 14 (DUSP14) acts as a negative regulator of NF-κB signalling. However, its function in hepatic I/R injury is unknown.
Hepatocyte-specific Dusp14 knockout (HKO) and transgenic (TG) mice were subjected to hepatic I/R surgery to examine Dusp14 function in vivo. Primary hepatocytes isolated from Dusp14-HKO and Dusp14-TG mice were cultured and subjected to hypoxia/reoxygenation insult in vitro. Inflammatory cytokine production was measured using quantitative reverse transcription PCR and ELISA. Liver damage was analysed using histopathology. Co-immunoprecipitation and pull-down assays followed by Western blot were performed to detect Dusp14 and transforming growth factor (Tgf)-β-activated kinase 1 (Tak1) interactions.
Dusp14 was significantly downregulated in liver tissues from liver transplantation patients and mice subjected to hepatic I/R surgery. Dusp14-HKO and Dusp14-TG mouse models demonstrated that Dusp14 reduced cell death, ameliorated inflammation, and promoted hepatocyte proliferation and/or regeneration. Dusp14 also suppressed NF-κB and MAPK signalling via a physical interaction with Tak1, leading to its subsequent inhibition. Tak1 inhibition by 5Z-7-ox abolished Dusp14 function in vivo, indicating that TAK1 is required for Dusp14 function in hepatic I/R injury. Finally, mutant Dusp14 lost the ability to bind Tak1 and failed to protect against hepatic I/R injury.
Dusp14 is a protective factor in hepatic I/R injury, and the Dusp14-Tak1-Jnk1/2 regulatory axis is important for the pathogenesis of hepatic I/R injury. Modulation of this axis could be a novel therapeutic strategy to prevent or interfere with this pathological process.
Reductions in the level of the protein Dusp14 are closely associated with liver damage caused by inadequate blood supply followed by restoration of blood flow to the liver. Dusp14 protects against liver damage by suppressing the activity of Tak1. Targeting Dusp14 could be a strategy for prevention and treatment of this disease.
肝缺血再灌注（I/R）损伤的特征为严重炎症反应和广泛细胞死亡。多种信号通路，包括核因子κB（NF-κB）和丝裂原活化蛋白激酶（MAPK）/c-Jun氨基末端激酶（JNK），在此过程中发挥重要作用。识别这些信号通路中未知的关键调节因子可为治疗应用提供潜在靶点。双特异性磷酸酶14（DUSP14）作为NF-κB信号通路的负调节因子。然而，其在肝I/R损伤中的功能尚不清楚。
构建肝细胞特异性Dusp14基因敲除（HKO）和转基因（TG）小鼠，进行肝I/R手术以检测Dusp14在体内的功能。分离Dusp14-HKO和Dusp14-TG小鼠的原代肝细胞，体外进行缺氧/复氧损伤。采用定量逆转录PCR和酶联免疫吸附测定法检测炎性细胞因子的产生。通过组织病理学分析肝损伤情况。进行免疫共沉淀和下拉试验，随后进行蛋白质印迹法检测Dusp14与转化生长因子（Tgf）-β激活激酶1（Tak1）的相互作用。
肝移植患者和接受肝I/R手术小鼠的肝组织中Dusp14显著下调。Dusp14-HKO和Dusp14-TG小鼠模型表明，Dusp14可减少细胞死亡、减轻炎症，并促进肝细胞增殖和/或再生。Dusp14还通过与Tak1直接相互作用抑制NF-κB和MAPK信号通路，进而抑制其活性。5Z-7-氧代（5Z-7-ox）抑制Tak1可消除Dusp14在体内的功能，表明TAK1是Dusp14在肝I/R损伤中发挥功能所必需的。最后，突变型Dusp14失去与Tak1结合的能力，无法预防肝I/R损伤。
Dusp14是肝I/R损伤中的保护因子，Dusp14-Tak1-Jnk1/2调节轴对肝I/R损伤的发病机制至关重要。调节该轴可能是预防或干预这一病理过程的新治疗策略。
蛋白质Dusp14水平降低与肝脏血液供应不足后恢复血流所导致的肝损伤密切相关。Dusp14通过抑制Tak1的活性来保护肝脏免受损伤。靶向Dusp14可能是预防和治疗该疾病的一种策略。
